Drilling with casing or liners instead of conventional drill pipe has been shown to increase the strength of a wellbore as measured by the difference in weight of the drilling fluid (“mud”) that can be circulated through a given formation during drilling of the formation and after continued drilling past the formation without losing mud to the formation (“lost circulation”). For example, wells drilled using casing in Piceance Basin in Colorado found improvements of more than 3 pounds per gallon (ppg) in formations that were initially experiencing lost circulation when drilling the particular formation. This experience was discussed in detail in a paper written by R. Watts, et al. and published in 2010 by the International Association of Drilling Contractors and Society of Petroleum Engineers as IADC/SPE 128913 (“the '913 paper”).
The exact mechanism for the wellbore strengthening that occurs while drilling with casing is not completely known, but is understood to result from the casing (or liner) smearing cuttings and other drilling fluid solids into small fractures in the wellbore as the casing and centralizers rotate against the wellbore during drilling. This is commonly referred to as the “smear effect.” As discussed in the '913 paper, the wellbore strengthening occurred over time as the drilling with casing continued. In the strengthening period, lost circulation to the formation still occurred. Any acceleration of the wellbore strengthening effect of drilling with casing would be valuable for the reduced amount of expensive mud lost to the formation, time spent on slower drilling in order to wait for the effect, and the ability to increase mud weight for safety ahead of drilling through higher pressure formations that could produce dangerous kicks of hydrocarbons, without setting a casing/liner separating the two formations.